Microphytic crusts,shrub patches and water harvesting in the Negev Desert: the Shikim system

Human-made contour banks are a central component of theShikim water harvesting system in Israels Negev Desert.Efficient water capture depends on the presence of a stable microphytic crustwhich directs surplus surface runoff into the banks where it is stored. We usedsimulated rainfall to examine the impact of soil surface disturbance on runoffand sediment transport, and the effect of this on the efficiency of resourcecapture within the Shikim system. Two disturbance regimes:1) removal of the microphytic crust only, and 2) removal of the crust and shrubpatches by cultivation, were compared with an undisturbed control. In theundisturbed state, 32% of rainfall was redistributed as runoff. This runoffpenetrated approximately 27% deeper under the shrub patches compared with themicrophytic crust. When the microphytic crust was destroyed by simulatedtrampling, the runoff coefficient declined to 13%, and there was no significantdifference in water penetration between shrub and crust patches. Completedestruction of the shrub hummocks and crust by cultivation resulted in adeclinein the runoff coefficient to 6%. The result of sustained disturbance in thesepatchy Negev shrublands is a breakdown in spatial heterogeneity, a loss ofecosystem function, a reduction in ecosystem goods and services such as plantdiversity and production, and ultimately a reduction in pastoral productivity.These results reinforce the view that microphytic crusts are critical for theefficient operation of the Shikim water harvesting system.Given that practices such as cultivation and trampling which disturbmicrophyticcrusts result in enhanced infiltration, crusts should be left intact tomaximisethe water harvesting efficiency in these desert landscapes.This revised version was published online in May 2005 with corrections to the Cover Date.     

Response to Insulin Treatment and Survival in 104 Cats with Diabetes Mellitus (1985–1995)

Medical records of 104 cats with diabetes mellitus were reviewed. Information from 54 cats that had multiple blood glucose concentrations evaluated at least 5 times over a minimum of 3 months, beginning at the time insulin treatment was initiated, was used to evaluate the efficacy of insulin in treating diabetes mellitus. Fourteen of 54 cats were treated with protamine zinc insulin (PZI), 26 with ultralente insulin, and 14 with lente insulin. Six, 29, and 19 cats had good, mediocre, and poor glycemic control, respectively, based on mean blood glucose concentrations, whereas 31, 21, and 2 owners thought clinical response was good, mediocre, and poor, respectively. No significant difference was found in glycemic control among cats treated with PZI, ultralente, or lente insulin. Glycemic control was significantly (P < .05) better in 33 cats without than in 21 cats with concurrent disease. All 104 cats were used to calculate survival data. Fifty-one of 104 cats were alive at the time of the study. Mean (± standard deviation [SD]) and median survival times were 24 (± 16) and 20 months, respectively, in the 51 cats still alive at the end of the evaluation, and 25 (± 4) and 17 months, respectively, in the 53 cats that had died during the period of evaluation. Pancreatic abnormalities identified in 37 cats that underwent necropsy included chronic pancreatitis (n = 17), acute to subacute pancreatitis (n = 2), exocrine pancreatic adenocarcinoma (n = 7) and adenoma (n = 1), islet cell atrophy and vacuolar degeneration (n = 27), and islet amyloidosis (n = 8). No association was found between glycemic control and islet amyloidosis or exocrine pancreatic neoplasia, or between survival time and chronic pancreatitis, islet amyloidosis, or exocrine pancreatic neoplasia. In conclusion, diabetic cats evaluated in this study showed a variable response to exogenously administered insulin, ranging from excellent to poor. By maintaining mean blood glucose concentrations under 300 mg/dL, clinical signs were improved, and owners were satisfied with insulin treatment. Concurrent potentially insulin-antagonistic diseases were common and deleteriously affected glycemic control and survival time.     

Measurement of canine plasma fibronectin by rocket immunoelectrophoresis

Plasma fibronectin concentrations of 148 normal canine samples were measured by rocket immunoelectrophoresis. Electrophoresis was accomplished, using 2.0% rabbit anticanine fibronectin by volume in 0.7% agarose in buffer. Films were electrophoresed 18 hours in barbital buffer, 7.5 mA/film. The mean fibronectin concentration for normal citrated dog plasma was 290 micrograms/ml +/- 50 micrograms/ml.     

Glucose tolerance and insulin response in normal-weight and obese cats

Glucose tolerance and insulin response were evaluated in 9 normal-weight and 6 obese cats after IV administration of 0.5 g of glucose/kg of body weight. Blood samples for glucose and insulin determinations were collected immediately prior to and 2.5, 5, 7.5, 10, 15, 30, 45, 60, 90, and 120 minutes after glucose infusion. Baseline glucose concentrations were not significantly different between normal-weight and obese cats; however, mean +/- SEM glucose tolerance was significantly impaired in obese vs normal-weight cats after glucose infusion (half time for glucose disappearance in serum--77 +/- 7 vs 51 +/- 4 minutes, P less than 0.01; glucose disappearance coefficient--0.95 +/- 0.10 vs 1.44 +/- 0.10%/min, P less than 0.01; insulinogenic index--0.20 +/- 0.02 vs 0.12 +/- 0.01, P less than 0.005, respectively). Baseline serum insulin concentrations were not significantly different between obese and normal-weight cats. Insulin peak response after glucose infusion was significantly (P less than 0.005) greater in obese than in normal-weight cats. Insulin secretion during the first 60 minutes (P less than 0.02), second 60 minutes (P less than 0.001), and total 120 minutes (P less than 0.0003) after glucose infusion was also significantly greater in obese than in normal-weight cats. Most insulin was secreted during the first hour after glucose infusion in normal-weight cats and during the second hour in obese cats. The impaired glucose tolerance and altered insulin response to glucose infusion in the obese cats was believed to be attributable to deleterious effects of obesity on insulin action and beta-cell responsiveness to stimuli (ie, glucose).     

Splenectomy as adjunctive therapy for immune-mediated thrombocytopenia and hemolytic anemia in the dog

Splenectomy was done in 9 dogs having immune-mediated hematologic disorders refractory to medical therapy. These disorders were immune-mediated thrombocytopenia (n = 3), immune hemolytic anemia (n = 3), and Evan's syndrome (n = 3). The diagnoses were based on clinical observations, laboratory test data, and differential of other conditions. In the 12 months after splenectomy was done, the dogs reflected clinical improvement and return of platelet and/or erythrocyte counts to clinically acceptable limits; medical treatment was stopped or reduced in 8 of 9 patients. The exceptional patient had shown clinical improvement without change in the platelet count. At the end of 1 year, survival rate was excellent, and postsplenectomy complications, such as hemobartonellosis, did not appear. It is believed that splenectomy may be useful for treating immune-mediated thrombocytopenia, anemia, and Evan's syndrome that seem refractory to medication.     

Glycosylated Hemoglobin Concentration for Assessment of Glycemic Control in Diabetic Cats

Blood glycosylated hemoglobin (GHb) concentration was quantified in 84 healthy cats, 9 cats with stress-induced hyperglycemia, 37 cats with newly diagnosed diabetes mellitus, and 122 diabetic cats treated with insulin or glipizide. Diabetic control was classified as good or poor in insulin-treated or glipizide-treated cats based on review of history, physical examination findings, changes in body weight, and measurement of blood glucose concentrations. Blood GHb concentration was determined using an affinity chromatography assay. Mean blood GHb concentration was similar for healthy normoglycemic cats and cats with transient, stress-induced hyperglycemia, but was significantly (P < .001) higher in untreated diabetic cats when compared with healthy normoglycemic cats. Mean blood GHb concentration was significantly (P < .001) higher in 84 cats with poorly controlled diabetes mellitus when compared with 38 cats in which the disease was well controlled. Mean blood GHb concentration decreased significantly (P < .01) in 6 cats with untreated diabetes mellitus after insulin and dietary treatment. A similar significant (P < .01) decrease in mean blood GHb concentration occurred in 7 cats with poorly controlled diabetes mellitus after diabetic control was improved by an increase in insulin dosage from 1.1 ± 0.9 to 1.4 ± 0.6 U/kg/ 24 h and by feeding a diet containing increased fiber content and in 6 cats with transient diabetes mellitus 8.2 ± 0.6 weeks after discontinuing insulin treatment. There was a significant (P< .01) stress-induced increase in mean fasting blood glucose concentration and mean blood glucose concentration for 12 hours after administration of insulin or glipizide but no change in mean blood GHb concentration in 5 docile diabetic cats 12.2 ± 0.4 weeks after the cats became fractious as a result of frequent hospitalizations and blood samplings. Results of this study suggest that evaluation of blood GHb concentration may be a clinically useful tool for monitoring glycemic control of diabetes in cats.     

Nephrotic syndrome: a platelet hyperaggregability state

Nephrotic syndrome characterized by hypoalbuminemia and hyperlipidemia is associated with an increased incidence of thromboembolism and increased platelet hyperaggregability. Although plasma coagulation proteins are also abnormal, changes are too inconsistent to attribute thromboembolic complications to the coagulation cascade alone. Antithrombin III (ATIII) has been shown to be deficient in nephrotic syndrome. There is, however, an increase in alpha 2 macroglobulin. It is clear that platelet to platelet interactions require exposure of platelet fibrinogen receptors, the binding of fibrinogen to these receptors, platelet crossbridging, and subsequent platelet aggregation. Fibrinogen is consistently elevated in nephrotic syndrome. Hyperlipidemia and hypoalbuminemia in nephrotic syndrome increases the availability of thromboxane A2 (TxA2) by increasing the availability of TxA2 precursors and the removal of TxA2 inhibitors. Thromboxane A2 is a known inducer of platelet aggregation probably through the exposure of platelet fibrinogen receptors. Recently, fibronectins a group of adhesive proteins, were implicated in platelet to platelet interactions. Since thrombin increases the expression of platelet surface fibronectin, fibronectin may be involved in thrombus formation in nephrotic syndrome. Thromboembolic formation in nephrotic syndrome is a composite mechanism involving the coagulation cascade, platelet-platelet interactions, and platelet-surface interactions.     

Drug-induced thrombocytopenia

A variety of drugs may cause thrombocytopenia. Although it occurs more often than drug-induced anemia it is less well understood because techniques for studying drug-platelet-immune interactions have been unavailable until recently. The mechanisms by which drugs cause thrombocytopenia are varied. Bone marrow suppression or increased peripheral destruction of platelets could be involved. Nonimmunologic as well as immunologic mechanisms may also occur. These different mechanisms of drug-induced thrombocytopenia are reveiwed. Diagnostic methods and treatment are also summarized.     

A Large‐scale,Rapid Public Health Response to Rabies in an Organ Recipient and the Previously Undiagnosed Organ Donor

This article describes and contrasts the public health response to two human rabies cases: one organ recipient diagnosed within days of symptom onset and the transplant donor who was diagnosed 18 months post‐symptom onset. In response to an organ‐transplant‐related rabies case diagnosed in 2013, organ donor and recipient investigations were conducted by multiple public health agencies. Persons with potential exposure to infectious patient materials were assessed for rabies virus exposure. An exposure investigation was conducted to determine the source of the organ donor's infection. Over 100 persons from more than 20 agencies spent over 2700 h conducting contact investigations in healthcare, military and community settings. The 564 persons assessed include 417 healthcare workers [5.8% recommended for post‐exposure prophylaxis (PEP)], 96 community contacts (15.6% recommended for PEP), 30 autopsy personnel (50% recommended for PEP), and 21 other persons (4.8% recommended for PEP). Donor contacts represented 188 assessed with 20.2% recommended for PEP, compared with 5.6% of 306 recipient contacts recommended for PEP. Human rabies cases result in substantial use of public health and medical resources, especially when diagnosis is delayed. Although rare, clinicians should consider rabies in cases of encephalitis of unexplained aetiology, particularly for cases that may result in organ donation.     

Isotopic evidence and quantification assessment of in situ RDX biodegradation in the deep unsaturated zone

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is an explosive compound whose extensive use has resulted in significant contamination of soils and groundwater worldwide. We studied its in situ biodegradation along the unsaturated zone beneath an explosives wastewater lagoon using compound-specific isotope analysis (CSIA) of RDX in the unsaturated zone, together with biodegradation slurry experiments under anaerobic conditions. We found the highest degradation potential of RDX and its nitroso derivatives in the upper part of the soil profile while in the lower parts, RDX-degradation potential was lower and the nitroso derivatives tended to persist. This was also observed in the field, as reflected by the isotopic composition of RDX along the profile. We also found a correlation between biodegradation potential and clay content: biodegradation was further enhanced in layers characterized by high-clay content or in those influenced by the high-clay layers. In addition, in the presence of high organic matter content, further enhancement of biodegradation was observed. We obtained different isotopic enrichment factors (?) for RDX biodegradation in different sections of the unsaturated profile and suggest that different degradation pathways exist simultaneously in situ, in variable proportions. Using the range of enrichment factors, we were able to assess the biodegradation extent of RDX at different sampling points along the profile, which ranged between 30 and 99.4%. The novel application of CSIA together with slurry experiments provides better insight into degradation processes that are otherwise difficult to detect and assess.